Don’t feel guilty. You have a life. You have stuff to do. Unless the blog is related directly to a job or a responsibility, do what you need to do. Example: if Pavonine were the official mascot of a convention, and your blog was an official blog for that convention, you would have a responsibility to update it regularly because it would be a job. However, Pavonine is YOUR character (and is not monetized in any way) so your real life, safety and wellbeing takes priority over any Tumblr blog.